The present invention relates to a radiation-emitting semiconductor body with a vertical emission direction.
A radiation-emitting semiconductor laser of this kind is known for example from the document WO 02/13334 A2. Described therein is a vertically emitting laser in the form of a so-called VCSEL (Vertical Cavity Surface Emitting Laser). This VCSEL comprises a semiconductor body with a laser resonator formed by two resonator mirrors and with, inter alia, an active layer and a current constricting layer disposed in the laser resonator. The current constricting layer serves in operation to concentrate the operating current on a small subarea of the active layer in order to create in that subarea the population inversion necessary for laser operation.
Such surface-emitting VCSELs excel in terms of their high radiation quality, but have a comparatively low optical output power. In addition, as described in the above-cited document, the current conduction must be well defined, since otherwise, due to the proximity of the current path and the laser resonator volume, combined with the comparatively small lateral expansion of a semiconductor laser of this kind, the electrical heat losses could have a negative impact on beam quality and stability.
It is further known to increase optical output power by providing, instead of a laser resonator integrated into the semiconductor body, a resonator equipped with an external resonator mirror. Such devices are also known as VECSELs (Vertical External Cavity Surface Emitting Lasers). Such semiconductor lasers having an external resonator usually exhibit far greater lateral expansion than a VCSEL and are operated at correspondingly higher powers. Thus, the diameter of a VECSEL is typically in the range of 10 μm or above. Due to the large difference in lateral dimensioning, designs for the conduction of operating current in a VCSEL usually cannot be transposed to a VECSEL.